Geographical distribution of soil transmitted helminths and the effects of community type in South Asia and South East Asia – A systematic review

Abstract

BackgroundSoil-transmitted helminth (STH) infections are among the most prevalent neglected tropical diseases (NTD) worldwide. Since the publication of the WHO road map to combat NTD in 2012, there has been a renewed commitment to control STH. In this study, we analysed the geographical distribution and effect of community type on prevalence of hookworm, Trichuris and Ascaris in south Asia and south east Asia.MethodologyWe conducted a systematic review of open-access literature published in PubMed Central and the Global Atlas of Helminth Infection. A total of 4182 articles were available and after applying selection criteria, 174 studies from the region were retained for analysis.Principal findingsAscaris was the commonest STH identified with an overall prevalence of 18% (95% CI, 14–23%) followed by Trichuris (14%, 9–19%) and hookworm (12%, 9–15%). Hookworm prevalence was highest in Laos, Vietnam and Cambodia. We found a geographical overlap in countries with high prevalence rates for Trichuris and Ascaris (Malaysia, Philippines, Myanmar, Vietnam and Bangladesh). When the effect of community type was examined, prevalence rates of hookworm was comparable in rural (19%, 14–24%) and tribal communities (14%, 10–19%). Tribal communities, however, showed higher prevalence of Trichuris (38%, 18–63%) and Ascaris (32%, 23–43%) than rural communities (13%, 9–20% and 14%, 9–20% respectively). Considerable between and within country heterogeneity in the distribution of STH (I2 >90%) was also noted. When available data from school aged children (SAC) were analysed, prevalence of Ascaris (25% 16–31%) and Trichuris (22%, 14–34%) were higher than among the general population while that of hookworm (10%, 7–16%) was comparable.Conclusions/SignificanceOur analysis showed significant variation in prevalence rates between and within countries in the region. Highlighting the importance of community type in prevalence and species mix, we showed that tribal and rural communities had higher hookworm infections than urban communities and for ascariasis and trichuriasis, tribal populations had higher levels of infection than rural populations. We also found a higher prevalence of ascariasis and trichuriasis in SAC compared to the general population but comparable levels of hookworm infections. These key findings need to be taken into account in planning future MDA and other interventions.

Prevalence and Risk Factors of Ascaris lumbricoides, Trichuris trichiura and Cryptosporidium Infections in Elementary School Children in Southwestern China: A School-Based Cross-Sectional Study

“…This study reported the prevalence of A. lumbricoides , T. trichiura and Cryptosporidium infections in the elementary school children. The prevalence of Cryptosporidium infections in our study (2.40%) was comparable to the provincial estimate (2.96%) in Sichuan Province, China [ 15 ]. The prevalence of A. lumbricoides infection (10.0%), was similar to the national prevalence (12.7%) of the second national important parasitic disease survey from 2001 to 2004, but was lower than those of Guizhou Province (42.0%) and Sichuan Province (27.7%) [ 13 ].…”

“…Although, the prevalence of STH infections continuously decreased according to national surveillance data, A. lumbricoides and T. trichiura infections remain high in several underdeveloped regions in China [ 11 , 12 , 13 , 14 ]. A review of South and Southeast Asia demonstrates that school children have higher infection risks of A. lumbricoides (25%, 95% CI: 16–31%) and T. trichiura (22%, 95% CI: 14–34%) than the general population [ 15 ]. However, Cryptosporidium infection had been largely neglected and few studies had been conducted in the Yi ethnicity in SW China.…”

Contamination of animal-keeping premises with eggs of parasitic worms

“…Invasive diseases of farm animals are widespread throughout the world (Silver et al, 2018) and have a leading place in the overall morbidity structure, and have a significant impact on herd productivity (Nansen, 1987). The presence of exogenous forms of helminths in environmental objects worsens its veterinary-sanitary condition, and in some cases pose infestation threat to humans.…”

Shadow Puppets and Neglected Diseases: Evaluating a Health Promotion Performance in Rural Indonesia

“…It is estimated that nearly 1 in 5 people are infected with STH globally [ 1 ] with the highest concentration in Asia, where approximately one quarter of the population is believed to host at least one species [ 2 ]. STH are typically found in tropical and sub-tropical regions, particularly where poverty is rife such as rural communities with limited access to clean water, inadequate sanitation and poor hygiene behaviour [ 3 ]. Infection occurs primarily through ingestion of parasite eggs or skin contact with motile larvae in contaminated soil [ 4 ].…”

“…Soil-transmitted helminths have been reported across the Indonesian archipelago with an average prevalence of 31.8% during the period 2002 to 2009 [ 11 ]. A recent systematic review of STH in South Asia and South East Asia reported a countrywide prevalence for Indonesia of 22% for Ascaris , 20% for hookworm and 12% for Trichuris [ 3 ]. Poverty permeates many Indonesian rural communities where education levels are generally low, access to clean water and adequate sanitation is limited, most households lack latrines and open defecation is common [ 12 , 13 ].…”